1. Field of the Invention
The present invention relates to a label printer where a thermal head of thermal transfer system is used. 2. Description of the Prior Art
FIG. 1 shows an example of a label printer in the prior art. In a cabinet 1 of the label printer, a long ground paper 3 with a label 2 stuck thereon is wound around a ground paper winding shaft 4. In order to perform printing on the label 2, the ground paper 3 is drawn and then wound around a platen 5 positioned to the front side of the ground paper winding shaft 4. In order to guide the ground paper 3 drawn out of the ground paper winding shaft 4 onto the platen 5, a guide plate 6 is installed between these members. After the label 2 is printed by a thermal head as hereinafter described, the label 2 is separated from the ground paper 3 by bending the ground paper 3 using a separating plate 7 positioned to the front side of the platen 5. The ground paper 3 after separating the label 2 is wound to a ground paper taking shaft 9 positioned below the separating plate 7. A guide roller 10 is installed to guide the ground paper 3 from the separating plate 7 to the ground paper taking shaft 9.
A ribbon winding shaft 12 with an ink ribbon 11 wound thereon is positioned to the rear side of the platen 5 in the cabinet 1. The ink ribbon 11 is drawn and overlaid to the ground paper 3 on the platen 5. A pair of guide rollers 13 are installed to guide the ink ribbon 11 between the ribbon winding shaft 12 and the platen 5. The ink ribbon 11 is heated by a thermal head 14 installed near the platen 5, and the ink is transferred in thermal transfer onto the label 2. In order to feed the ink ribbon 11 and the label 2, the platen 5 and a drive motor 15 positioned above the platen 5 are connected through a belt 16 that rotates the platen 5, and the fed ink ribbon 11 is wound to a ribbon taking shaft 17 installed above the platen 5. Guide rollers 18, 19, 20 are installed to guide the ink ribbon 11 which is wound to the ribbon taking shaft 17 and separated from the ground paper 3.
Referring to FIG. 3, the guide roller 18 positioned between the platen 5 and the separating plate 7 guides the ink ribbon 11 so as to separate the ground paper 3 and the ink ribbon 11 on a portion of the platen 5. Consequently, the ink ribbon 11 and the label 2 adhered by heat of the thermal head 14 cannot be easily separated. Furthermore, the ink ribbon 11 is rubbed and charged by the guide roller 18 during travelling. Since the guide roller 18 attracts the label 2 by the charging, separation between the ink ribbon 11 and the ground paper 3 becomes further difficult. The separation between the ink ribbon 11 and the ground paper 3 may occur abruptly, and therefore the ground paper 3 may be vibrated and noise be produced. The instantaneous feed amount of the ground paper 3 may increase, thereby possibly bending the label 2 itself at its top end together with the ground paper 3 by the separating plate 7 so that the label 2 cannot be separated.